Whenever you install an NVIDIA
driver you have the chance to select the custom option, which deletes the old
driver and clean installs the new one.
As you have found out, it doesn't always pay to install the latest
driver.
You also have to consider that the OEM driver supplied by your computer manufacturer may be configured differently to one from NVIDIA.
Go to Uninstall Programs and uninstall any NVIDIA driver(s) you have installed then either let Windows Updates install a graphics driver or install the driver that Asus supply or download a driver from NVIDIA - the 275 version is trouble-free.